As is well known, the piano is a musical instrument played by means of a keyboard. In a conventional piano, pressing a key on the piano's keyboard causes a felt-covered hammer to strike steel strings. The hammers rebound, allowing the strings to continue vibrating at their resonant frequency. These vibrations are transmitted through a bridge to a sounding board that more efficiently couples the acoustic energy to the air. When the key is released, a damper stops the string's vibration. The invention of the modern piano is credited near the year 1700 to Bartolomeo Cristofori (1655-1731) of Padua, Italy, who was employed by Ferdinando de' Medici, Grand Prince of Tuscany, as the Keeper of the Instruments.
In the period lasting from about 1790 to 1860, the piano underwent tremendous changes that led to the modern form of the instrument. This revolution was in response to a preference by composers and pianists for a more powerful, sustained piano sound, and made possible by the ongoing Industrial Revolution with resources such as high-quality piano wire for strings, and precision casting for the production of iron frames. Over time, the tonal range of the piano was also increased, e.g., from five octaves to the 7⅓ or more octaves found on modern pianos. Various other improvements also came slowly over the years, such as felt hammer coverings, double escapement action, the sostenuto pedal, a “choir” of three strings, an over-strung scale (also called “cross-stringing”), duplex scaling, etc.
In addition, some early pianos had shapes and designs that are no longer in use. For instance, the square piano (actually rectangular) was cross strung at an extremely acute angle above the hammers, with the keyboard set along the long side. Moreover, other designs included an upright grand, a cabinet piano, a short cottage upright piano or pianino with vertical stringing (informally called birdcage pianos), an oblique or diagonally strung upright, a tiny spinet upright, etc. Further designs also included giraffe, pyramid, and lyre pianos, which were arranged in a somewhat similar fashion in evocatively shaped cases. Modern upright and grand pianos attained their present forms by the end of the 19th century.
With the advent of modern technology, electronics have played a major role in recent advances in piano design. In particular, in addition to electric pianos, which simply use electromagnetic pickups to amplify the sound of the strings of a conventional piano, digital pianos use technology (e.g., digital sampling) to electrically reproduce the sound of each piano note, rather than using actual strings (e.g., metal tines, reeds, or strings hit by a hammer). Digital pianos can be sophisticated, with features including working pedals, weighted keys, multiple voices, and MIDI interfaces. That is, a digital piano is a modern electronic musical instrument, meant generally to provide an accurate simulation of a real piano, and may include a variety of piano timbres and many more instrument sounds including strings, guitars, organs, and more.
For instance, most digital pianos can be connected to a computer, e.g., using the MIDI interface. With appropriate software, the computer can handle sound generation, mixing of tracks, music notation, musical instruction, and other music composition tasks. Though piano-style musical keyboards are called “keyboards,” regardless of their functions or type, keyboards and other devices used to trigger musical sounds are often called “controllers,” because with most MIDI set-ups, the keyboard or other device does not make any sounds by itself. That is, controllers (or MIDI controllers) need to be connected to a voice bank or sound module in order to produce musical tones or sounds.
Furthermore, some digital pianos incorporate other basic “synthesizer” sounds such as string ensemble, and offer settings to combine them with piano. A sound synthesizer (often abbreviated as “synthesizer” or “synth”), for instance, is an electronic instrument capable of producing a wide range of sounds, which may either imitate other instruments or generate new timbres. Synthesizers are often controlled with a piano-style keyboard, leading such instruments to also be referred to simply as “keyboards.”
Yet another form of piano/keyboard is the “stage piano,” designed for use with a live band. Stage pianos often have a heavier, more robust body, which is better able to withstand the stress of heavy touring. Unlike digital pianos designed for home use, they do not have a fixed stand or fixed sustain pedals. Instead, they are designed to be used with a separate portable stand and portable sustain pedals, to aid in transportation between shows.
The physical form of a digital piano can vary considerably. Most vaguely resemble a low upright piano (e.g., without an enclosed lower section), while still others are based on the casework of traditional upright or grand instruments. Other types of digital pianos, such as the controllers, keyboards, synthesizers, stage pianos, etc., generally merely comprise various encasement designs to house the necessary physical components (e.g., keys, action mechanisms, etc.) and electronics, placed on some type of stand. Despite their variations in design of their external housing, however, all digital piano keyboards are currently based on the typical arrangement and orientation of traditional piano keys. That is, all of their keys are parallel, planar, and linear.